Ebola became infamous as the virus became rampant throughout western Africa in 2014. By October 2014, there were over 100 0 new cases reported each week. A year later, the number had decreased to less than 10. Ebola virus disease (EVD) was easily transmitted through bodily fluids, even after death, leading to the devastating ease at which the disease spread and claimed lives. One mode of transmission that poses a threat after this epidemic is semen. Survivors were told to only have intercourse with a condom for at least 3 months following recovery. The 3 month waiting period was determined from previous epidemics, in which the longest the virus remained in semen after symptoms onset was only 82 days. However, when a women in Liberia had confirmed EVD in March of 2015, further questioning revealed the only potential exposure she had was intercourse with a male EVD survivor. After testing, the survivor’s semen contained Ebola RNA 199 days after symptom onset. Though it wasn’t infectious virus, it still warranted an investigation into the idea that Ebola could be transmitted through survivor’s semen as much as 6 months after symptom onset.
The Sierra Leona Ministry of Health and Sanitation, as well as Ministry of Social Welfare, the WHO, and the CDC designed a study in the Western Area District of Sierra Leone. Samples were taken form 100 male survivors, all of which were 18 years or older and had laboratory confirmation of EVD at their time of illness. Participants were compensated for every visit and completed a questionnaire about their health, sexual behavior, demographics, and their EVD illness. The participants were an average of 30 years old and none had an positive HIV, tuberculosis or diabetes diagnosis. Both pre and post test counseling was given to participants, each lasting about 2 weeks, that included information on safe sexual habits, as well as the test that was being performed and the results. After semen samples were taken, a quantitative RT-PCR was performed. The samples were tested for EVD specific genes NP and VP40, as well as human B2M gene. Both NP and VP40 had to be detected, as well as B2M.
A total of 93 of the 100 participants had useable samples and data. 10% of the men had reported a time of 2-3 months from illness onset, 43% reported 4-6 months, 46% reported 7-9 months, and only 1 man reported 10 months. 46 out of the 93 men had positive RT-PCR results. These 46 men included all 9 of the 2-3 month range, 26 men of the 4-6 month range, and 11 men of the 7-9 month range. The 10 month range man had results that were indeterminate. The longest amount of time passed from illness onset that still yielded a positive RT-PCR result was 9 months, and the shortest time was 4 months. However, the shortest amount of time it took to yield a negative result was 100 days, or 3 months.
Though theses results indicated that EVD RNA might be present in semen longer than initially thought, the presence of this RNA does not necessarily mean there is infectious virus present. However, the detection of these RNA sequences might indicate the full genome is present from a replicating virus. Future experiments are planning to use virus-isolation assay, which will allow scientists to observe if these specimens have cytopathic effects when are they are inoculated onto cell cultures. This will be more telling of the infectious capacities of these semen samples. These experiments will also test for longer periods of time, as this study only successfully observed a maximum time period of 10 months after illness onset.
Lena Chatterjee is the 2015-2016 Research Highlights Editor.